PS2 (Ext)-6
Students demonstrate an understanding of physical, chemical, and nuclear changes by... 6aa-using chemical equations and information about molar masses to predict quantitatively the masses of reactants and products in chemical reactions.
National Standards:
Context of Lesson:
This is a 90 minute lesson designed to introduce the idea of percent composition to students. Students will be given reasons why percent composition is useful and then be given example and practice problems to reinforce the concepts presented.
Opportunities to Learn:
Depth of Knowledge
Prerequisite Knowledge
Students should know how to:
Calculate the molar mass of a compound
Work with percentages (or have a little background knowledge)
Plans for Differentiating Instruction
Some students may experience more difficulty with mathematical concepts. To help the students learn the many calculations in this chapter, they should write out a step-by-step procedure in their own words for doing each of the sample problems. Then they should ask the instructor or a peer to read and, if necessary, correct their procedures. What about providing some additional practice problems?
Accommodations and modifications
Environmental factors
There is a smartboard in the front of the room which will be used for working problems. Desks are in rows.
Materials
Students will need their required materials (notebook, textbook, calculator, pen/pencil)
Objectives:
Students will be able to calculate the percent composition of a substance from its chemical formula or experimental data.
Instruction:
Opening:
Explain to students that knowing the relative amounts of a mixture is very useful. Proceed to ask them to come up with 1 or 2 examples of times when we would want to know the amount of something in a given mixture. Take about five or six responses. What questions will you ask? This seems like you are going to tell them "what you will be learning today is important." How did you respond to this approach as a student?
Engagement:
Use the following example to reinforce the students responses:
When people feed their lawns in the spring they want a fertilizer with a higher percentage of Nitrogen to keep the grass looking green.
When people feed their lawns in the fall, before the grass hibernates, they try to strengthen the roots with a fertilizer with a higher percentage of Potassium.
So, in order to pick the most appropriate fertilizer we must know the percent composition of each of these elements contained in the compound that makes up the fertilizer.
Excellent example. (for the suburbs at least.) Why not have them read a passage and determine this summary for themselves and have them answer the question: What do you need to know to formulate fertilizer for the spring and fall? Then you'd be in a position to define percent composition.
Define percent composition as: The relative amounts of each element in a compound that are expressed as percentages or, more simply, the percent by mass of each element in a compound.
Give the following example: K2CrO4 consists of K = 40.3%, Cr = 26.8%, and O = 32.9% all totaling 100%. Why not start with the formula and challenge students to determine percent of each substance? Give them a change to figure it out before you tell them. Now how do we calculate these percents? Answer: Mass of element (in grams)/Mass of entire compound (in grams) x 100% = % mass of element
Give students example problem 7-10 (p. 189): An 8.20g piece of magnesium combines completely with 5.40 g of oxygen to form a compound. What is the percent composition of this compound? Demonstrate how to solve the problem. You should say something to break up the period. Practice time is another activity. Will they work in groups or individually. What will be expected of them at the end of this work time?
Assign the following practice problems:
9.03g of Mg combine completely with 3.48 g of N to form a compound. What is the percent composition of this compound?
29.0 g Ag combine completely with 4.30g S to form a compound. What is the percent composition of this compound?
As students are working on these walk around to monitor their progress. When the majority of the class is finished have them put the problems up on the board and explain their solutions. After they have completed the problems give them the following notes:
If we wanted to calculate the percent composition of a known compound we do the following: Why not have them work in groups to develop and share a "problem solving protocol?"
First, use the chemical formula to calculate the molar mass (mass of one mole of the compound).
Second, for each element, determine the molar mass.
Third, calculate the percent by mass in one mole of the compound by dividing the mass of each element by the total molar mass of the compound and multiply the result by 100%.
Assign the following practice problems: Calculate the percent composition of these compounds
Ethane (C2H6)
Sodium bisulfate (NaHSO4)
Ammonium chloride (NH4Cl)
As students are working walk around to assist and monitor their progress. When the majority of students are finished have volunteers put the problems up on the whiteboard/smartboard and explain what they have done to solve the problem.
If time permits, give the students the following worksheet:
If you are running short on class time the worksheet can be completed for homework and gone over the following class.
Closure:
Briefly go over the concepts of percent composition reviewing what was accomplished in class, i.e. how do we calculate the percent composition of a compound? Why is this useful? Give students a brief overview of the following class's lesson (Using Percent as a Conversion Factor). Explain that they will also be doing Part II of the laboratory exercise. If the worksheet on percent composition was not completed in class assign it for homework so that you will be able to go over it in the beginning of the next class period. It would be nice if you could show the students that spring and fall fertilizer did indeed have different components that contain different percentages of the substances mentioned at the beginning of class.
Assessment:
Students will be formatively assessed via posing questions, which can be found throughout the lesson, that will test their knowledge on current material. They will also have a worksheet that will be due at the beginning of the following class which will be collected, graded, passed back and briefly gone over.
Lesson Plan
Lesson Title: Percent Composition
State Standards: GLEs/GSEs
PS2 (Ext)-6Students demonstrate an understanding of physical, chemical, and nuclear changes by...
6aa-using chemical equations and information about molar masses to predict quantitatively the masses of reactants and products in chemical reactions.
National Standards:
Context of Lesson:
This is a 90 minute lesson designed to introduce the idea of percent composition to students. Students will be given reasons why percent composition is useful and then be given example and practice problems to reinforce the concepts presented.Opportunities to Learn:
Depth of Knowledge
Prerequisite Knowledge
Students should know how to:Plans for Differentiating Instruction
Some students may experience more difficulty with mathematical concepts. To help the students learn the many calculations in this chapter, they should write out a step-by-step procedure in their own words for doing each of the sample problems. Then they should ask the instructor or a peer to read and, if necessary, correct their procedures. What about providing some additional practice problems?Accommodations and modifications
Environmental factors
There is a smartboard in the front of the room which will be used for working problems. Desks are in rows.Materials
Objectives:
Instruction:
Opening:
Explain to students that knowing the relative amounts of a mixture is very useful. Proceed to ask them to come up with 1 or 2 examples of times when we would want to know the amount of something in a given mixture. Take about five or six responses. What questions will you ask? This seems like you are going to tell them "what you will be learning today is important." How did you respond to this approach as a student?Engagement:
Use the following example to reinforce the students responses:- When people feed their lawns in the spring they want a fertilizer with a higher percentage of Nitrogen to keep the grass looking green.
- When people feed their lawns in the fall, before the grass hibernates, they try to strengthen the roots with a fertilizer with a higher percentage of Potassium.
- So, in order to pick the most appropriate fertilizer we must know the percent composition of each of these elements contained in the compound that makes up the fertilizer.
Excellent example. (for the suburbs at least.) Why not have them read a passage and determine this summary for themselves and have them answer the question: What do you need to know to formulate fertilizer for the spring and fall? Then you'd be in a position to define percent composition.Define percent composition as: The relative amounts of each element in a compound that are expressed as percentages or, more simply, the percent by mass of each element in a compound.
Give the following example: K2CrO4 consists of K = 40.3%, Cr = 26.8%, and O = 32.9% all totaling 100%. Why not start with the formula and challenge students to determine percent of each substance? Give them a change to figure it out before you tell them. Now how do we calculate these percents? Answer: Mass of element (in grams)/Mass of entire compound (in grams) x 100% = % mass of element
Give students example problem 7-10 (p. 189): An 8.20g piece of magnesium combines completely with 5.40 g of oxygen to form a compound. What is the percent composition of this compound? Demonstrate how to solve the problem.
You should say something to break up the period. Practice time is another activity. Will they work in groups or individually. What will be expected of them at the end of this work time?
Assign the following practice problems:
- 9.03g of Mg combine completely with 3.48 g of N to form a compound. What is the percent composition of this compound?
- 29.0 g Ag combine completely with 4.30g S to form a compound. What is the percent composition of this compound?
As students are working on these walk around to monitor their progress. When the majority of the class is finished have them put the problems up on the board and explain their solutions. After they have completed the problems give them the following notes:If we wanted to calculate the percent composition of a known compound we do the following:
Why not have them work in groups to develop and share a "problem solving protocol?"
- First, use the chemical formula to calculate the molar mass (mass of one mole of the compound).
- Second, for each element, determine the molar mass.
- Third, calculate the percent by mass in one mole of the compound by dividing the mass of each element by the total molar mass of the compound and multiply the result by 100%.
Assign the following practice problems: Calculate the percent composition of these compounds- Ethane (C2H6)
- Sodium bisulfate (NaHSO4)
- Ammonium chloride (NH4Cl)
As students are working walk around to assist and monitor their progress. When the majority of students are finished have volunteers put the problems up on the whiteboard/smartboard and explain what they have done to solve the problem.If time permits, give the students the following worksheet:
If you are running short on class time the worksheet can be completed for homework and gone over the following class.
Closure:
Briefly go over the concepts of percent composition reviewing what was accomplished in class, i.e. how do we calculate the percent composition of a compound? Why is this useful? Give students a brief overview of the following class's lesson (Using Percent as a Conversion Factor). Explain that they will also be doing Part II of the laboratory exercise. If the worksheet on percent composition was not completed in class assign it for homework so that you will be able to go over it in the beginning of the next class period. It would be nice if you could show the students that spring and fall fertilizer did indeed have different components that contain different percentages of the substances mentioned at the beginning of class.Assessment:
Students will be formatively assessed via posing questions, which can be found throughout the lesson, that will test their knowledge on current material. They will also have a worksheet that will be due at the beginning of the following class which will be collected, graded, passed back and briefly gone over.Reflections
(only done after lesson is enacted)Student Work Sample 1 – Approaching Proficiency:
Student Work Sample 2 – Proficient:
Student Work Sample 3 – Exceeds Proficiency: